1. Field of the Invention
The present invention relates to a shooting game system and an external storage used therefor. More particularly, it relates to a shooting game system adapted as to display a target on a raster scan type display and shoot the target displayed with a shooting scope, and an external storage used therefor.
2. Description of the Prior Art
Shooting game system adopted to shoot a target displayed on a television receiver with a shooting scope, such as the shooting game system disclosed in U.S. Pat. No. 4,395,045 (hereinafter referred to as first prior art) and the shooting game system disclosed in Japanese Patent Laid-Open Gazette No. 171063/1985 (corresponding U.S. Pat. No. 4,813,682) (hereinafter referred to as second prior art) have been conventionally known.
In the above described first prior art, an image of a target displayed on a television receiver is detected on the side of a shooting scope, and its detection pulse is transmitted to a computer connected to the television receiver. The computer detects a coordinate position which is shot on the screen of the television receiver on the basis of the phase difference between the detection pulse received and synchronizing signals (horizontal and vertical synchronizing signals) of the television receiver.
The above described second prior art is a adapted as to display a character of a target in white and a background in black when a trigger switch of a shooting scope is depressed, and determines if there is a "hit" depending on whether or not an image of this character is detected by the shooting scope.
The first prior art is a adapted as to correct the coordinate position which is shot by the shooting scope on the screen of the television receiver when a hit determination is made. The reason for this is that an optical axis of the barrel of the shooting scope and a sighting axis of a gunsight do not exist on the same straight line, so that there occurs a shift between the optical axis and the sighting axis on the screen of the television receiver. However, this correction processing is performed using a fixed correction value. Therefore, the first prior art has the disadvantage in that no fixed correction can be made and inaccurate hit determinations are is made in cases, for example, where an angle at which a player looks into the gunsight deviates from a previously presumed angle or an angle which the optical axis of the barrel forms with the sighting axis of the gunsight deviates from a previously presumed angle due to a manufacturing error, and the distance between the television receiver and the shooting scope deviates from a previously presumed distance.
Furthermore, the first prior art also has the disadvantage in that an optical system provided for the shooting scope and an optical system provided for the computer are easily adversely affected by ambient light from the exterior (for example, due to illuminating light of a fluorescent lamp or the like or due to substantial adjustment of the luminance of the television receiver), and an error is liable to occur in detection of a light receiving signal from the target of the television receiver.
On the other hand, the second prior art has the disadvantage in that the precision of hit determination is low when a small target is shot because a coordinate position which is shot by the shooting scope can be only detected for each character.
Furthermore, the second prior art has the disadvantage in that an accurate hit judgment can not be made when an optical axis of the barrel of the shooting scope and a sighting axis of a gunsight are shifted because the coordinate position which is shot is not corrected.